feat: make skills invokable as slash commands in the TUI

- Add Skill.content() method to load skill template content from SKILL.md files
- Modify Command.list() to include skills as invokable commands
- Add 'skill' boolean property to Command.Info schema
- Update autocomplete to show skills with (Skill) label in slash commands
- Regenerate SDK to include skill property in Command type

packages/opencode/src/cli/cmd/tui/component/prompt/autocomplete.tsx

@@ -345,8 +345,9 @@ export function Autocomplete(props: {
     const results: AutocompleteOption[] = [...command.slashes()]
 
     for (const serverCommand of sync.data.command) {
+      const label = serverCommand.mcp ? " (MCP)" : serverCommand.skill ? " (Skill)" : ""
       results.push({
-        display: "/" + serverCommand.name + (serverCommand.mcp ? " (MCP)" : ""),
+        display: "/" + serverCommand.name + label,
         description: serverCommand.description,
         onSelect: () => {
           const newText = "/" + serverCommand.name + " "